1. Field of the Invention
The invention relates generally to electronic component chassis and more specifically to a chassis for electronic components, such as a computer chassis, in which a power supply has a cooling system which is isolated from other components.
2. Description of the Related Art
It is well known to house various electronic components in an enclosure. In many instances, a power supply for providing operating voltage and current to the components is also housed in the enclosure. The phrase “power supply” as used herein, refers generally to a device having a primary purpose of generating and/or regulating electric operating power supplied to active electronic components. All electronic components other than power supplies are referred to merely as “components” herein. Typically, all electronic components dissipate heat to some degree. Further, power supplies by nature dissipate a relatively large amount of heat as compared to components.
One example of electronic components housed with a power supply is a computer chassis. Typically, a computer chassis includes a power supply housed in the same enclosure as various computer components, such as motherboards having central processing units (CPUs), memory devices, communication interface devices, and the like. The phrase “computer component” as used herein, refers to any component that is housed in an enclosure of a computer chassis, except for the power supply.
As computers become more ubiquitous in society, it becomes more desirable to reduce the size of computer chassis. Currently, there is a clear trend toward more powerful and more compact computer chassis. Accordingly, the consumed power per unit density, i.e. the power density, of the average computer has increased tremendously over the past several years. However, such an increase in power density runs into a limitation of heat dissipation. More specifically, the higher the power density, the more heat generated and the more difficult it is to dissipate the heat. Of course, heat adversely affects the operation of most microprocessor based components and other components. Accordingly, the desire to reduce the size and increase the power of computers is at odds with the need to maintain components at temperatures within desired operating ranges. Further, the presence of a power supply in the same enclosure as computer components can adversely effect the operation of the computer components because of the large amount of heat dissipated by the power supply and the generally disparate heat rates and characteristics of power supplies as compared to computer components.
Essentially, there are two processes by which heat in a computer enclosure is dissipated. The first process is fluid exchange cooling which consists of replacing a heated fluid, such as air, in the enclosure with a cooler fluid, e.g. ambient air. The second process is forced cooling in which the fluid is moved across the surface of a specific component to raise the convective heat transfer coefficient for the surface of the component thereby cooling the component faster than if the component was in static fluid. Most computer enclosures incorporate both heat dissipation processes to some degree. Both processes require the movement of air.
It is well known to use fans or blowers to move air through computer enclosures to cool various components therein. Conventionally, such devices are placed in a front panel or a back panel of the computer enclosure. However, the presence of a power supply serves to create excess heat in the enclosure that tends to raise the operating temperature of other components in the enclosure. Accordingly, conventional computer chassis include a relatively large fan that is sized for the entire heat producing system, i.e. the power supply and the computer components in the chassis. The large fan wastes precious enclosure and panel space. Further, fans themselves generate heat and thus oversized fan generates excessive heat.
It is known to take advantage of various ducts in computer chassis. For example, U.S. Pat. No. 6,094,345 discloses a computer enclosure having a duct that extends between external portions of the enclosure and includes an air intake that is open to internal portions of the enclosure. Air is drawn into an external intake and the internal intake for cooling the power supply. The air drawn in the internal intake has been heated by other components in the enclosure.
U.S. Pat. No. 5,432,674 discloses a computer enclosure having a duct extending between the front and back panels of the enclosure. A fan forces air through the duct to cool a power supply. The duct includes an exhaust opening into an interior of the enclosure for cooling other components. Accordingly, the air used to cool the components has been heated by the power supply.